Histologic examination of the biopsy specimen showed a superficial perivascular and interstitial infiltrate of lymphocytes. The epidermis was spongiotic and exhibited basal vacuolar degeneration and some necrotic keratinocytes. Melanophages were observed in the upper dermis.

The patient was diagnosed as having PP, with a typical clinical picture and supportive histologic findings. Minocycline hydrochloride therapy (100 mg/d) was initiated, and the eruption resolved within 2 weeks. No recurrence was observed during 10 months of follow-up.